Pedal assemblies are used to control movement of a vehicle. Typically pedal assemblies include mechanical connections to the respective vehicle system that the pedal controls. For example, a mechanical connection for an accelerator pedal usually includes a bracket and cable-connect to an engine throttle. The rotary movement of the pedal is transferred to the engine throttle via the cable. The cable controls the position of the engine throttle based on the position of the pedal. Similar mechanical connections are used for brake and clutch pedals.
These pedal assemblies have a desirable feel experience by the operator due to hysteresis feedback provided by the mechanical linkage interconnecting the accelerator pedal and the fuel throttle. With a mechanical linkage, the pedal pressure required when advancing the accelerator pedal is greater than that required to maintain a fixed position. This difference is often referred to as the hysteresis effect. This effect is importance for reducing operator fatigue.
As vehicles incorporate more electrically control vehicle systems, attempts have been made to provide an electrical link between the pedal and the vehicle system to be controlled. Mechanical connections are often bulky and difficult to package within the limited space available in the vehicle. The components in the mechanical linkages are also subject to wear and can bind or stick causing the vehicle system to become inoperable. The electrical link eliminates the need for mechanical linkage parts and thus, reduces cost and increases packaging space for other vehicle components.
Some pedals incorporating electric control utilize contact sensors such as potentiometers to generate the control signal as the pedal pivots between various operational positions. One disadvantage with the use of contact sensors is that they tend to wear over time, which can affect the accuracy of the control signal.
An example of a pedal incorporating a contact sensor electric control is shown in U.S. Pat. Nos. 5,697,260 and 5,819,593. The pedal assemblies include a pedal arm that is pivotally mounted within a housing that is supported by a vehicle structure. The pedal arm pivots with respect to the housing as a force is applied to a pedal connected to one end of the pedal arm. The pedal assemblies include a separate sensor assembly, such as a potentiometer, that is installed within the housing. The sensor assembly generates an electric signal that varies in proportion to the movement of the pedal arm with respect to the housing.
Another example of a pedal with a contact sensor electric control is shown in U.S. Pat. No. 5,768,946. A separate sensor module is installed within the housing. The sensor module includes a electrical connector for connection to the vehicle system to be controlled. As discussed above, the sensor module is used to sense the position of the pedal and generates an electric signal that varies as the pivotal pedal position varies. Typically, these sensor modules are potentiometers. The potentiometers are sensitive to dirt and other contaminants and thus must be provided in a sealed environment in order to operate properly. The sensor modules are thus, self-contained and are installed into the pedal housing as a sealed component. The sensor modules are expensive and bulky. The pedal housing must be specially designed to accommodate these large sensor modules, which is undesirable.
Sometimes non-contact sensors such as Hall effect sensors are used to generate the control signal. An example of a pedal incorporating a non-contact type sensor for electric control is shown in U.S. Pat. No. 5,439,275. The pedal assembly includes a Hall Effect sensor used in combination with magnets mounted within a plunger to generate an output signal that varies according to pedal position. As the pedal is pivoted, the plunger moves in a linear direction with respect to the sensor resulting in a varying magnetic field. In such a configuration it is difficult to convert rotational pedal input movement into an accurate linear output from the sensor, which can be used to control the vehicle system.
Thus, it would be desirable to have an improved pedal assembly with a non-contact sensor that can use rotational pedal input to produce a linear output that corresponds to pedal deflection so that an accurate control signal can be used to control the corresponding vehicle system. It would be also desirable to have a more compact pedal assembly with integrated non-contact sensing components that do not require a separate sensor housing while still providing a sealed environment to keep out dirt and other components. The pedal assembly with integrated non-contact sensing components should also include a resistance assembly for generating a hysteresis effect that is sealed within the same housing. This would improve packaging and reduce cost and assembly time for the pedal.